Apparatus for controlled contraction of collagen tissue

ABSTRACT

A method and apparatus applies radiant energy through the skin to an underlying subcutaneous layer or deeper soft tissue layers that includes loculations of fat with fibrous septae made of collagen tissue. This creates a desired contour effect without substantially modifying melanocytes and other epithelial cells in the epidermis. A membrane conforms a contacting exterior surface of the membrane to a skin layer. One or more thermal electrodes positioned in the membrane. A focussing element focuses thermal energy to the underlying collagen tissue. The focusing element and the electrolytic solution create a reverse thermal gradient from the skin to the collagen tissue. A thermal power source is coupled to the thermal electrodes.

CROSS-REFERENCE TO RELATED CASES

This application is a divisional of application Ser. No. 08/435,544,filed May 5, 1995 now U.S. Pat. No. 5,660,836.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally for achieving contour sculpting andmore particularly to a method and apparatus that creates a reversethermal gradient in order to achieve contour sculpting through partialdenaturation of collagen without ablation of the collagen and withoutaffecting the melanocytes and other epithelial cells.

2. Description of Related Art

The skin is the one organ of the body that is readily available forinspection by the eyes and fingers of every living person. It issubjected to considerable abuse such as exposure to extremeenvironmental of cold, heat, wind, and sun.

The surface layer of the skin is called the epidermis. It is the barrierthat prevents most substances from entering the body from outside whilepreventing body fluids from entering equilibrium with the environment.The basilar layer of the epidermis includes the melanocytes and otherepithelial cells.

The melanocytes are small cells with a small, dark staining nucleus anda clear cytoplasm. Melanin in packaged in distinctive granules isproduced by these cells and transferred then air dendritic processes toadjacent keratinocytes. The purpose of melanin is to protect the skinfrom the ravages of ultraviolet radiation. Beneath the epidermis is thepapillary dermis and reticular dermis. Collagen tissue is found in thedermal and the sub dermal tissues.

There has been a large market for tightening the skin in order to reduceaging effects and effects created by exposing the skin to extremeenvironmental forces. To date there are two primary methods fortightening skin. The first is surgical skin excision. The second ischemical burn. When skin is surgically excised it leaves large scares.This is generally not a satisfactory solution for many skin tighteningapplications. With chemical peel treatments the process is painful,there is damage to the melanocytes and other epithelial cells, thepatient maybe have spotted pigmentation, or with most of the melanocytesand other epithelial cells destroyed the patient can have apredominately white complexion. In the chemical peel method a thermalgradient is created which is hotter at the surface of the epidermis andcooler at the sub dermal layers. With the creation of this type ofthermal gradient there is a great likelihood of modification ordestruction of the melanocytes and other epithelial cells, resulting inblotchiness or an inability to tan in the future.

Collagen molecules are produced by fiborblasts which synthesize threepolypeptide chains that wrap around one another in a triple helix. Eachof the chains is approximately 1000 amino acid units in length, withglycine recurring regularly every third unit and hydroxyproline andproline recurring very frequently. Cross-linking occurs between theside, not the ends, of collagen molecules and is coupled with the aminoacid composition to give collagen its great strength. Collagen tissueshrinkage takes place in a direction parallel to an axis of collagenfibers.

The phenomenon of thermal shrinkage of collagen begins with adenaturization of the triple helix of the collagen molecule. Partialdenaturization of collagen tissue results in a shrinkage of the collageand provides a “tightening” effect on the overlaying skin. To date therehave been no devices or methods for contracting the underlying collagentissue through partial denaturization without damaging the melanocytesand other epithelial cells in the epidermis.

Adipose tissue, more commonly known as fat, is formed of cellscontaining stored lipid. Adipose tissue is often subdivided into smalllobules by connective collagen tissue serving as the fibrous septae.

Adipose tissue is widely distributed in the subcutaneous tissue butexhibits regional differences in amount partially because of age andsex. Excess adipose tissue can be physically undesirable from bothhealth and cosmetic perspective. A current method for the removal offatty tissue is the extraction of adipose tissue by liposuction. This isa purely mechanical method with undesirable side effects due to theinvasive nature of the process.

Another method of removing fatty tissue is disclosed in U.S. Pat. No.5,143,063 (“the '063”). The method of the '063 patent targets adiposetissue absorbs sufficient energy resulting in cell destruction anddeath. The method of the '063 patent fails to minimize damage to themelanocyte in the epidermis. Thus, with the method of the '063 patentcan create unwanted blotchiness or changes in the melanocytes and otherepithelial cells.

There exists the need for skin tightening without damaging themelanocytes and other epithelial cells, or without surgicalintervention. There is a further need for non-surgically removingadipose tissue without damaging the melanocytes and other epithelialcells.

SUMMARY OF THE INVENTION

It is an object of the present invention is to provide a method andapparatus for creating a reverse thermal gradient that utilizes one ormore RF electrodes, an electrolytic solution to transfer RF energy fromthe RF electrodes to the epidermis and underlying layers, and whereinthe apparatus includes a lumen adapted to receive a cooling fluid.

It is another object of the present invention to provide a method andapparatus for non surgically reducing loculations of fat withoutsubstantially damaging the melanocytes and other epithelial cells.

Another object of the present invention is to provide a method andapparatus for non surgically reducing loculations of fat with the use ofa thermal energy source that does not substantially effect themelanocytes and other epithelial cells.

A further object of the present invention is to provide a method andapparatus for contour sculpture, by utilizing a reverse thermal gradientto partially denature collagen in fibrous septae tissue.

These and other objects of the invention are provided in an apparatusfor applying radiant energy through the skin to an underlyingsubcutaneous layer, and deeper soft tissue layers, such as the muscleand overlying fascia, include loculations of fat with fibrous septaemade of collagen tissue. Application of the radiant energy creates adesired contour effect without substantially modifying the melanocytesand other epithelial cells in the epidermis. The apparatus includes amembrane that conforms a contacting exterior surface of the membrane toa skin layer. One or more thermal electrodes are positioned in themembrane and create a reverse thermal gradient from the skin layer tothe underlying collagen tissue. A focussing element focuses thermalenergy to the underlying collagen tissue. The focussing element and theelectrolytic solution create a reverse thermal gradient from the skin tothe collagen tissue. A thermal power source is coupled to the thermalelectrodes.

Further, a method of liposulpturing a layer under the skin comprised ofa loculation of fat which has collagen tissue as a fibrous septaeincludes providing a membrane and a thermal energy source. A reversethermal gradient is created which cools the top surface of the skinwhile heating the underlying loculation of fat. This is achieved withoutsubstantially modifying the melanocytes and other epithelial cells inthe epidermis. Collagen tissue of the fibrous septae is partiallydenatured and contracted with a diminished destruction of cells.

Radiant energy is applied to a variety of different skin layersincluding the papillary dermis layer, the reticular dermis layer, andeven to a subcutaneous layer and to underlying soft tissue. One suitableenergy source is one or more RF electrodes. Electrolytic solutiontransfers RF energy from the RF electrodes to the underlying collagentissue. The cooling fluid can create a reverse thermal gradient at theepidermis to underlying desired layers of about 30 degrees to about 80degrees C. The apparatus can further include one or more thermal sensorspositioned on the contacting exterior surface of the membrane, as wellas one or more impedance monitors. Further, the apparatus can include afeedback device which is responsive to a detected characteristic of theskin or subcutaneous layer in order to provide a control delivery of RFenergy from the RF electrodes. A variety of detected characteristics canbe monitored including impedance measurements of the skin andtemperature profiles of the skin.

The feedback device can also include a controller as well as amultiplexer.

The creation of the reverse thermal gradient provides for the controlledcontraction of collagen tissue, e.g., partial denaturization of thecollagen molecules that results in a shrinkage of the collagen tissue,which then extends to a shrinkage of the skin. Creation of the reversethermal gradient is different from other methods of collagen contractionwhich typically employ a thermal gradient that has a higher temperatureat the surface and decreases with the depth of penetration.

The apparatus of the present invention that creates the desired contoureffect by the modification of collagen tissue surrounding loculations offat can include a focussing element to help direct the energy past theepidermis and into the fat containing layers. The apparatus can furtherinclude a coupling device that couples the focussing element to themembrane, as well as a bracket which is positioned around the peripheryof the membrane and also supports the focussing elements. Instead ofkilling cells, thermal lipolysis is utilized with a cooling blanket onthe skin so that thermal destruction fat cells, and the melanocytes andother epithelial cells are minimally damaged.

A variety of thermal energy sources can be employed. Suitable energysources include but are not limited to RF, microwave, ultrasound and thelike. In one embodiment, the preferred energy source is RF.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of an apparatus for applying radiant energythrough the skin in order to cause a partial denaturization of collagentissue, resulting in a tightening of the skin.

FIG. 2 is a cross-sectional view of the skin and underlying tissue.

FIG. 3 is a schematic representation of the collagen network.

FIG. 4 is a schematic diagram of an apparatus for applying radiantenergy to underlying subcutaneous layers or deeper soft tissue layers tocreate a desired contour effect by partially denaturing collagen tissue,and without substantially modifying melanocytes and other epithelialcells in the epidermis.

FIG. 5 is a block diagram of an RF system which can be utilized with thepresent invention.

FIG. 6 is a block diagram of processing circuit of one embodiment of theinvention.

DETAILED DESCRIPTION

The present invention provides an apparatus for applying radiant energythrough the skin to underlying collagen tissue without substantiallymodifying the melanocytes and other epithelial cells found in theepidermis.

The present invention also provides an apparatus for applying radiantenergy through the skin to underlying subcutaneous or deeper soft tissuelayers that include loculations of fat with fibrous septae made ofcollagen tissue. Application of the radiant energy creates an desiredcontour effect of the loculations of fat without substantially modifyingthe melanocytes and other epithelial cells in the epidermis. Further,non invasive methods are providing for skin tightening and tighteningthe fibrous septae around the loculations of fat to create the desiredcontour effect.

The methods of the present invention do not provide for total necrosisof cells. Instead, with the method and apparatus creating the desiredcontour effect, the loculations of fat with the fibrous septae made ofcollagen tissue use a reverse thermal gradient applied to the underlyingcollagen tissue layers resulting in a partial denaturization of thecollagen permitting it to become tightened. This is achieved withoutkilling all of the fat cells within the loculations.

Various types of radiant energy can be utilized with the presentinvention. Radiant energy may be any kind that can cause cell heating orphysical destruction by being applied to collagen tissue. Examples ofsuitable radiant energy source include, but are not limited to RF,microwave, ultrasound, and the like.

Referring now to FIG. 1, an apparatus 10 applies radiant energy througha skin layer 12, such as the epidermis, and to the underlying collagentissue 14 without substantially modifying melanocytes and otherepithelial cells 16 found in the lower layer of epidermis layer 12.

A porous membrane 18 is adapted to receive an electrolytic solution 20.Porous membrane 18 becomes inflated to substantially conform acontacting exterior surface 22 of porous membrane 18 which is in closethermal contact with epidermis 12. Porous membrane 18 includes a coolinglumen 24 for receiving a cooling fluid that imparts a cooling effect onepidermis layer 12.

One or more thermal electrodes 26 are positioned at various places inporous membrane 18. In one embodiment, thermal electrodes 26 arepositioned on a side that is substantially opposing to contactingexterior surface 22. In other embodiments, thermal electrodes 26 areplaced closer to cooling lumen 24. In embodiment particularly suitablefor the hips, porous membrane is about 20 cm by 30 cm, with an ovalshape.

A thermal power source 28 is coupled to thermal electrodes 26 and asource of electrolytic solution 30 is coupled to porous membrane 18.

With referenced now to FIG. 2, radiant energy can be applied throughepidermis layer 12, to papillary dermis layer 32, to reticular dermislayer 34, to subcutaneous layer 35, as well as to underlying soft tissue36. The extend of collage in the various layers is <5% in the epidermis,˜50% in the dermis, ˜20% in the subcutaneous, ˜5% in the muscle withoverlying fascia. Shrinking of collagen tissue takes place in adirection parallel to the axis of the collagen fibers. Thermal shrinkageof collagen begins with the denaturization of the triple helix structureof the collagen fibers. This occurs when thermal energy is applied tothe collagen tissue causing the hydrolysis of heat labial cross links ofthe collagen network.

FIG. 3 is a schematic representation of a collagen network behaviorunder the influence of heat. The thickened lines represent the chainsoriginally bound by covalent cross links. The arrows indicate tensionsexerted on the collagen chains by the effect of heat. More particularly,FIG. 3 illustrates (i). native collagen network 40, (ii). collagen 42under isometric conditions, (iii). collagen network without anyrestraint, (iv). collagen network 46 under isometric tension as long asthe nodes are stable, and (v). collagen network 48 under isometrictension after some cross links have been cleaved.

In one embodiment of the present invention, thermal electrodes 26 are RFelectrodes which can be a single electrode, or a plurality which canform a segmented flexible circuit. Thermal power source 28 is then an RFgenerator. Electrolytic solution 20 is introduced into porous membrane18 and passes by RF electrodes 26. Electrolytic solution 20 transfers RFpower from RF electrodes 28 to the desired underlying collagen tissue toachieve partial denaturization of the collagen molecule.

Generally, RF electrodes 926 can be monopular or bipolar. In themonopular mode, RF current flows through body tissue from a returnelectrode which can be in a form of a conductive pad applied to thepatients outer skin. Maximum heating occurs where the current density isthe greatest.

During a treatment phase, the denaturization of collagen molecules canbe conducted under feedback control. Treatment can occur without theattention of medical supervision. Feedback is accomplished by (i).visualization, (ii). impedance, (iii). ultrasound, or (iv). temperaturemeasurement. Optionally included and preferably positioned on contactingexterior surface 22 can be one ore more thermal sensors 52, as well asone or more impedance monitors 54. Thermal sensors 52 permit accuratedetermination of the surface temperature of epidermis layer 12.

Electrolytic solution 20 can be preheated to a selected temperature andmodified a necessary. This reduces the amount of time needed to effectat satisfactory denaturization of collagen molecules and subsequent skintightening.

Porous membrane 18 can be made of a material that is an insulator. Forpurposes of this disclosures, an insulator is a barrier to thermal orelectrical energy flow. Porous membrane 18 can be made of a materialwhich permits controlled delivery of electrolytic solution 20 toepidermis layer 12. Porous membrane 18 can be made of a variety ofmaterials including, but not limited to knitted polyester, continuousfilament polyester, polyester-cellulose, rayon, polyamide, polyurethane,polyethylene and the like. Suitable commercial products include, (i).Opcell available from Centinal Products Corp., Hyannis, Mass., and (ii).UltraSorb, HC 4201 or HT 4644 MD from Wilshire Contamination Control,Carlsbad, Calif. Pockets or zones 56 can be formed around RF electrodes26. Each pocket 56 has a lower porosity for the flow of electrolyticsolution 20 than all other sections of porous membrane 18. Differencesin porosity can be achieved with different types of materials which formporous membrane 18. Electrolytic solution 20 is retained in pockets 56longer than in non-pocket sections of porous membrane 18, and there is agreater transfer of RF energy to electrolytic solution 20, creating alarger electrode. The larger electrode produces RF and thermal energy tocreate a larger electrode effect. However, this does not effect thecreation of the reverse thermal gradient. RF energy is still transferredthrough porous membrane 18 passing in the vicinity of cooling lumen 24,in order to create a lower temperature at epidermis layer 12 and thetemperature increases as deeper layers are reached.

Referring now to FIG. 4, an apparatus 58 for creating a desired contoureffect of underlying subcutaneous layers or deeper soft tissue layerswhich include loculations of fat with fibrous septae made of collagentissue is illustrated. The apparatus 58 of FIG. 4, includes a porousmembrane 18, electrolytic solution 20, a contacting exterior surface 22,a cooling lumen, thermal electrodes 26, a thermal power source 28, anelectrolytic solution source 30, one or more thermal sensors 52, as wellas one or more impedance monitors 54. Apparatus 58 also includes afocussing element 60 which focuses thermal energy from electrolyticsolution 20 to the underlying collagen tissue. Focussing element 60 andelectrolytic solution 20 create a reverse thermal gradient fromepidermis layer 12 to the underlying collagen tissue 14. Focussingelement 62 can be, in the case of ultrasonic energy, a lens having aflat planer surface on the radiation wave incident side and a concaveexit face, see Ultrasonics Theory and Application, by G. L. Goberman,Heart Publishing Co., New York (1959), at section 2.6. The use of such afocussing lens for ultrasonic energy with a planer wave receiving faceand concave exit face is also described in the article “Deep LocalHypothermia for Cancer Therapy: Extreme Electromagnetic and UltrasoundTechnics,” A. Y. Cheung and A. Neyzari, Cancer Research, Vol. 44,pp.4736-4744, October 1984.

Radio frequencies can be the thermal energy source, and variouslocalizing technique, well known in the art, can be utilized. In oneembodiment, radio frequency energy is supplied by capacitive couplingdirectly to epidermis layer 12 for areas close to the dermal tissue.Radio frequency induction focussing can be achieved with the use ofplural focussing coils which are adaptive at the zone of interest andare elsewhere subtractive. Alternatively, radio frequency energy may befocused by having a multiple beam phased array. For concave focussingsee, “Tumor reduction by radio frequency therapy response”, H. H. Lavienet al., JAMA, Vol. 233, at 2198-2200.

Alternative radio frequency focussing methods are disclosed in“Equipment for Local Hypothermia Therapy of Cancer”, C. F. Babbs et al.,Medical Instrumentation, Vol. 16, No. 5, September-October 1982,pp.245-248.

It will be appreciated that focussing element 60 can be a convergentlens. Further, focussing element 60 can be positioned in porous membrane18, and at the exterior 16 between epidermis layer 12 and porousmembrane 18. Further, a coupling device 62 can be included which couplesfocussing element 60 with porous membrane 18. In one embodiment,coupling device 62 is a bracket which is positioned around a peripheryof porous membrane 18, and supports focussing element 50 in relation toporous membrane 18.

In the method for tightening skin, porous membrane 18 and thermal energysource 26 are provided. A reverse thermal gradient is created whichcools a surface of epidermis layer 12 while heating underlying collagencontaining layers. Epidermis layer 12 as well as underlying collagencontaining tissue are heated, without substantially effecting themelanocytes and other epithelial cells in epidermis layer 12, resultingin a denaturization of collagen molecules, causing a contraction of thecollagen tissue and a tightening of the skin. This method can be appliednumerous times. In many instances, it may be desirable to tighten theskin to a certain level and then in subsequent treatments the skin istightened further. There are may be four fine treatments to fine tunethe contour effects with greater precision. In this method, collagencontaining tissue is partial denatured and fat cell destruction isminimized. This is achieved by partially denaturing by cleaving heatlabial cross links of the collagen molecules.

The reverse thermal gradient provides a variation in temperaturethroughout the various tissue layers. For example, in one embodiment,the reverse thermal gradient is a temperature range from about 30degrees to about 80 degrees C., initiating from epidermis layer 12 tocollagen containing tissue layers. The reverse thermal gradient can havea temperature range of about 30 to 75 degrees C., and additionally fromabout 30 to 70 degrees C.

In another embodiment, a method for liposculpturing an area of the bodywhere there is an underlying area comprised of a loculation of fat thathas collagen tissue as a fibrous septae also includes creating a reversethermal gradient from epidermis layer 12 to the desired underlyingloculation of fat layer. Sufficient thermal energy is supplied throughepidermis layer 12, without damaging or substantially modifying themelanocytes and other epithelial cells, through other skin layers and isfocused on the collagen tissue of the fibrous septae. Thermal energypartially denatures the collagen tissue with a minimal destruction offat cells. Again, this is achieved by partially denaturizing, e.g., bycleaving, heat labial cross links of collagen molecules. The reversethermal gradient produces a net mobilization of intra-cellular fat withdiminished destruction of fat cells.

For purposes of illustration, without the scope of the invention let itbe assumed that power source 28 is an RF power source, an RF powersource 28, feeds energy to an RF power generator 64 and then to RFelectrodes 26. A multiplexer 66 measures current, voltage andtemperature, at the numerous thermal sensors associated with to each RFelectrode 26. RF electrodes 26 can be individually measured. Multiplexer66 is driven by a controller 68 which can be a digital or analogcontroller, or a computer with software. When controller 68 is acomputer it can include a CPU coupled through a system bus. On thesystem can be a keyboard, disk drive, or other non volatile memorysystems, a display, and other peripherals, as are well known in the art.Also coupled to the bus are a program memory and a data memory.

An operator interface 70 includes operator controls 72 and a display 74.Controller 68 can be coupled to different types of imaging systemsincluding ultrasonic, thermal sensors 52, and impedance monitors 54.

Current and voltage are used to calculate impedance. A diagnostic phasecan be initially run to determine the level of treatment activity. Thiscan be done through ultrasound as well as other means. Diagnostics canbe performed both before and after treatment.

Thermal sensors 52, and thermal sensors 76 contained within RF generator64 measure voltage and current that is delivered to the desiredtreatment site. The output for these sensors is used by controller 68 tocontrol the delivery of RF power. Controller 68 can also controltemperature and power. An operator set level of power and/or temperaturemay be determined and this will not be exceeded. Controller 68 maintainsthe set level under changing conditions. The amount of RF energydelivered controls the amount of power. A profile of power delivered canbe incorporated in controller 68, as well as a preset amount of energyto be delivered. Feedback can be the measurement of impedance,temperature, or other indicators and occurs either at control 68 or atRF generator 64, if it incorporates a controller. For impedancemeasurement, this can be achieved by supplying a small amount of nontherapeutic RF energy. Voltage and current are then measured to confirmelectrical contact.

Circuitry, software and feedback to controller 68 result in full processcontrol and are used to change, (i). power, (ii). the duty cycle, (iii).monopular or bipolar energy delivery, (iv). electrolytic solution 20delivery, flow rate and pressure and (v). can determine when the processis completed through time, temperature and/or impedance. These processvariables can be controlled and varied based upon tissue temperaturemonitored at multiple sites on contacting exterior surface 22 as well asmonitoring impedance to current flow at each RF electrode 26, indicatingchanges in current carrying capability of the tissue during the process.Further, controller 68 can provide multiplexing, monitor circuitcontinuity, and determine which RF electrode 26 is activated.

A block diagram of one embodiment of suitable processing circuitry isshown in FIG. 6. Thermal sensors 52 can be thermistors which have aresistance that varies with temperature. Analog amplifier 78 can be aconventional differential amplifier circuit for use with thermistors andtransducers. The output of analog amplifier is sequentially connected byan analog multiplexer 80 to the input of an analog digital converter 82.The output of amplifier 78 is a voltage which represents the respectivesensed temperatures. The digitized amplifier output voltages aresupplied by analog to digital converter 82 to a microprocessor 84.Microprocessor 84 calculates the temperature or impedance of the tissue.Microprocessor 84 can be a type 6800. However, it will be appreciatedthat any suitable microprocessor or general purpose digital or analogcomputer can be used to calculate impedance or temperature.

Microprocessor 84 sequentially receives and stores digitalrepresentations of impedance and temperature. Each digital valuereceived by microprocessor 84 corresponds to different temperatures andimpedances.

Calculated temperature and impedance values can be indicated on display74. Alternatively, or in addition to the numerical indication oftemperature or impedance, calculated impedance or temperature values canbe compared by microprocessor 84 with temperature and impedance limits.When the values exceed predetermined temperature or impedance values awarning can be given on display 74 and additionally, the delivery of RFenergy to its respective electrode can be decreased or multiplexed toanother electrode. A control signal from microprocessor 84 can reducethe power level by RF generator 64, or de-energize the power deliveredto any particular electrode. Controller 68 receives and stores thedigital values which represent temperatures and impedances sent.Calculated surface temperatures and impedances can be forwarded bycontroller 68 to display 74. If desired, the calculated surfacetemperature of epidermis layer 12 is compared with a temperature limitand a warning signal can be sent to display 74. Similarly, a controlsignal can be sent to RF power source 26 when temperature or impedancevalues exceed a predetermined level.

The foregoing description of a preferred embodiment of the invention hasbeen presented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formsdisclosed. Obviously, many modifications and variations will be apparentto practitioners skilled in this art. It is intended that the scope ofthe invention be defined by the following claims and their equivalents.

What is claimed is:
 1. A method of liposculpturing an area of the bodyincluding a skin with multiple layers, and an underlying area made of aloculation of fat that has collagen tissue as a fibrous septae,comprising: providing a thermal energy source; positioning an energydelivery surface of the thermal energy delivery source on an externalsurface of the skin; creating a reverse thermal gradient which cools atop surface of the skin while heating the underlying loculation of fat,wherein a temperature of the external skin surface is lower than atemperature of the underlying loculation of fat; heating the skin andunderlying loculation of fat sufficiently to contract the collagentissue of the fibrous septae while minimizing cellular destruction ofthe melanocytes; and tightening at least a portion of the externalsurface of the skin.
 2. The method of claim 1, wherein the collagencontaining tissue is partially denatured by cleaving heat labilecross-links of collagen molecules.
 3. The method of claim 1, wherein thecollagen containing tissue is partially denatured while minimizingcellular destruction.
 4. The method of claim 1, wherein the reversethermal gradient produces a net mobilization of intracellular fat withdiminished destruction of cells.
 5. The method of claim 1, wherein thethermal energy source is an RF power source and one or more RFelectrodes are positioned in a membrane.
 6. The method of claim 5,further comprising: a source of electrolytic solution that deliverselectrolytic solution to the RF electrodes.
 7. The method of claim 6,wherein RF energy is transferred from the RF electrodes to theelectrolytic solution.
 8. The method of claim 7, further comprising: acooling fluid lumen positioned in the membrane.
 9. The method of claim8, further comprising a source of cooling medium that is introduced intothe cooling fluid lumen.
 10. The method of claim 1, wherein the collagentissue is in a subdermal layer.
 11. The method of claim 1, wherein thecollagen tissue is in a deep dermal layer.
 12. The method of claim 1,wherein the collagen tissue is in a subcutaneous layer.
 13. The methodof claim 1, wherein the collagen tissue is in fascial and muscle tissue.